Understanding Plant Names

Genus / Species
Malus floribunda is in the same genus as apples. Its species name means "mass of flowers".
Variety
Dictamnus albus var. purpureus has purplish flowers instead of the white of the species.
Hybrid
The x symbol after the genus name in Osmanthus x burkwoodii denotes its hybrid status.
Cultivar
The species parentage of plants like Osteospermum 'Buttermilk' is complex and therefore not given.
Cultivar of species
Osphiopogon planiscapus 'Nigrescens' is an unusual form cultivated for its black leaves.
Seed series
Antirrhinum Sonnet Series is a mixture of brightly colored cultivars for summer bedding.


Sure it can seem confusing, since even the name of the name has more than one name... botanical name, scientific name, Latin name, binomial name, all are used, seemingly interchangeably. The American Horticultural Society helps demystify the plant name in the Great Plant Guide.

Throughout the AHS Great Plant Guide, all plants are listed by there current botanical names. The basic unit of plant classification is the species, with a two-part name correctly given in italic text: the first part is the genus, and the second part is the species name, or "epithet."

Genus
A group of one or more plants that share a wide range of characteristics, such as Chrysanthemum or Rosa, is known as a genus. A genus name is quite like a family name, because it is shared by a group of individuals that are closely related. Hybrid genera (crosses between plants derived from two genera, such as x Cupressocyparis), are denoted by the x symbol before the genus name

Species
A group of plants capable of breeding together to produce similar offspring are known as a species. In a two-part botanical name, the species epithet distinguishes a species from other plants in the same genus, rather like a given name. A species epithet usually refers to a particular feature of that species, such as tricolor (of three colors), or it may refer to the person who first discovered the plant.

Subspecies, Variety, and Forma
Naturally occurring variants of a species - subspecies, variety, or forma - are given an additional name in italics, prefixed by "subsp.", "var.", or "f". All of these are concerned with minor divisions of species, differing slightly in their botanical structure or appearance.

Hybrids
If different species within the same genus are cultivated together, they may cross-breed, giving rise to hybrids sharing attributes of both parents. This process is exploited by gardeners who wish to combine valued characteristics of two distinct plants. The new hybrid is then increased by propagation. An example is Camellia x williamsii which has the parents C. japonica and C. saluensis.

Cultivars
Variations of a species that are selected or artificially raised are given a vernacular name. This appears in single quotation marks after the species name. Some cultivars are also registered with trademark names, often used commercially instead of the the valid cultivar name. If the parentage is obscure or complex, the cultivar name may directly follow the generic name - Iris 'Muse's Visit'. In a few cases, particularly roses, the plant is known by a popular selling name, which is not the correct cultivar name; here, the popular name comes before the cultivar name, as in Rosa BONICA 'Meidomonac'.

Groups and Series
Several very similar cultivars may, for convenience, be classified in named Groups or Series that denote their similarities. Sometimes, they can be a deliberate mixture of cultivars of the same overall character but with flowers in different colors.

So, for the name of the name, let's go with what seems to be working for the good folks over at AHS, botanical name it is, for now.